How this calculator works
A unit rate divides an amount by the corresponding quantity. The same relationship can be rearranged to recover either total. Keep the entered quantities in consistent units before calculation: labels describe the answer but do not perform conversions. The quantity must be positive. A signed amount or rate can represent a signed change.
Formula
rate = amount/quantity; amount = rate times quantity; quantity = amount/rate.
Worked example
150 dollars for 3 kilograms is 50 dollars per kilogram. If 12 litres are used at 4 litres per minute, the corresponding quantity is 3 minutes.
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Frequently asked questions
Do the labels convert units?
No. Convert measurements first, then use the labels to describe the entered units.
Can I compare package prices?
Yes. Calculate each price per the same quantity unit, such as dollars per kilogram.
Why is a zero quantity invalid?
An amount per zero units involves division by zero. Recovering a quantity also requires a non-zero rate.